BDE-47 disrupts axonal growth and motor behavior in developing zebrafish.

Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental pollutants detected in a wide variety of environmental matrixes and pose a significant public health concern. 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) is one of the most predominant PBDE congeners in environmental media, biota and human tissues. However, few studies have explored the BDE-47 developmental neurotoxicity and underlying mechanisms. In this study, zebrafish (Danio rerio) embryos were waterborne exposed to BDE-47 at 1.25, 5, 20 μM starting from 6h post-fertilization (hpf). Motor behavior development and swimming behavior in response to light-to-dark photoperiod stimulation were studied at various developmental stages. Our data indicate that BDE-47 exposure significantly affected spontaneous movement, decreased touch response and free swimming speed, altered larvae swimming behavior in response to light stimulation in developing zebrafish. Consistent with these motor deficits, BDE-47 significantly inhibited axonal growth of primary and secondary motor neurons during the early developmental stages, suggesting the functional relevance of structural changes. Our findings demonstrate that the altered patterns of neuronal connectivity may contribute to motor behavior deficits, indicating the relevance of zebrafish as a model for studying toxicant developmental neurotoxicity.